 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.registry;

 import java.io.File ;
 import java.lang.ref.SoftReference ;
 import org.eclipse.core.runtime.IContributor;

 /**
  * An object which represents the user-defined extension point in a
  * plug-in manifest.
  */
 public class ExtensionPoint extends RegistryObject {
     public static final ExtensionPoint[] EMPTY_ARRAY = new ExtensionPoint[0];

     //Place holder for the label and the schema. It contains either a String[] or a SoftReference to a String[].
 //The array layout is [label, schemaReference, fullyQualifiedName, namespace, contributorId]
 private Object extraInformation;
     //Indexes of the various fields
 private static final byte LABEL = 0; //The human readable name for the extension point
 private static final byte SCHEMA = 1; //The schema of the extension point
 private static final byte QUALIFIED_NAME = 2; //The fully qualified name of the extension point
 private static final byte NAMESPACE = 3; //The name of the namespace of the extension point
 private static final byte CONTRIBUTOR_ID = 4; //The ID of the actual contributor of the extension point
 private static final int EXTRA_SIZE = 5;

     protected ExtensionPoint(ExtensionRegistry registry, boolean persist) {
         super(registry, persist);
     }

     protected ExtensionPoint(int self, int[] children, int dataOffset, ExtensionRegistry registry, boolean persist) {
         super(registry, persist);

         setObjectId(self);
         setRawChildren(children);
         setExtraDataOffset(dataOffset);
     }

     protected String getSimpleIdentifier() {
         return getUniqueIdentifier().substring(getUniqueIdentifier().lastIndexOf('.') + 1);
     }

     private String [] getExtraData() {
         //The extension point has been created by parsing, or does not have any extra data
 if (noExtraData()) { //When this is true, the extraInformation is always a String[]. This happens when the object is created by the parser.
 if (extraInformation != null)
                 return (String []) extraInformation;
             return new String [EXTRA_SIZE];
         }

         //The extension point has been loaded from the cache.
 String [] result = null;
         if (extraInformation == null || (result = ((extraInformation instanceof SoftReference ) ? (String []) ((SoftReference ) extraInformation).get() : (String []) extraInformation)) == null) {
             result = registry.getTableReader().loadExtensionPointExtraData(getExtraDataOffset());
             extraInformation = new SoftReference (result);
         }
         return result;
     }

     /**
      * At the end of this method, extra information will be a string[]
      */
     private void ensureExtraInformationType() {
         if (extraInformation instanceof SoftReference ) {
             extraInformation = ((SoftReference ) extraInformation).get();
         }
         if (extraInformation == null) {
             extraInformation = new String [EXTRA_SIZE];
         }
     }

     protected String getSchemaReference() {
         String [] result = getExtraData();
         return result[1] == null ? "" : result[SCHEMA].replace(File.separatorChar, '/'); //$NON-NLS-1$
 }

     protected String getLabel() {
         String [] result = getExtraData();
         return result[0] == null ? "" : result[LABEL]; //$NON-NLS-1$
 }

     protected String getUniqueIdentifier() {
         return getExtraData()[QUALIFIED_NAME];
     }

     public String getNamespace() {
         return getExtraData()[NAMESPACE];
     }

     protected String getContributorId() {
         return getExtraData()[CONTRIBUTOR_ID];
     }

     public IContributor getContributor() {
         return registry.getObjectManager().getContributor(getContributorId());
     }

     void setSchema(String value) {
         ensureExtraInformationType();
         ((String []) extraInformation)[SCHEMA] = value;
     }

     void setLabel(String value) {
         ensureExtraInformationType();
         ((String []) extraInformation)[LABEL] = value;
     }

     void setUniqueIdentifier(String value) {
         ensureExtraInformationType();
         ((String []) extraInformation)[QUALIFIED_NAME] = value;
     }

     void setNamespace(String value) {
         ensureExtraInformationType();
         ((String []) extraInformation)[NAMESPACE] = value;
     }

     void setContributorId(String id) {
         ensureExtraInformationType();
         ((String []) extraInformation)[CONTRIBUTOR_ID] = id;
     }

     public String toString() {
         return getUniqueIdentifier();
     }

 }

